Alert archive / California / Flash Flood Warnings in 1998

Flash Flood Warning 69, NWS San Francisco Bay Area, CA

February 21, 1998San Mateo County, Santa Cruz County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 21, 1998, 2:30 PM PST for San Mateo County, Santa Cruz County, California. It was in force for 5 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Feb 21, 1998, 2:30 PM PST (22:30 UTC)
Expired
Feb 21, 1998, 7:00 PM PST
In force
5 hr
Issued by
NWS San Francisco Bay Area, CA
Area
Whole counties

Counties San Mateo County, CA, Santa Cruz County, CA

The radar

The San Francisco radar (KMUX), 27 km from the middle of the area, began a volume at 22:32 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Oakland, CA (KOAK), launched 12:00Z, 10.5 hours before the alert went out and 56 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Oakland, CA at 12:00Z on 1998-02-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 12:00Z on 1998-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 354 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
688 m above ground
0-6 km bulk shear
80 kt
0-1 km storm-relative helicity
354 m²/s²
0-3 km storm-relative helicity
516 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

The office that day

Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 21, 9:45 AM PSTFlash Flood WarningMTRAmador2 hr
Feb 21, 9:45 AM PSTFlash Flood WarningMTRRiverside2 hr
Feb 21, 12:00 PM PSTFlash Flood WarningMTRRiverside3 hr
Feb 21, 12:00 PM PSTFlash Flood WarningMTRAmador3 hr

Nearby

Flash Flood Warnings in California, 1998Every flash flood warning in 1998

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.